1. Field of the Invention
The present invention relates to a video and audio recording apparatus and an editing method suitable for, for example, overwriting video data and audio data recorded in a recording medium in order to edit the data.
2. Description of the Related Art
In general, digital video data and/or digital audio data (hereinafter also referred to as “AV data”) captured by a video camera and recorded in a recording medium are edited as necessary. In short, in the editing operation, a desired video clip is extracted from playback AV data in a recording medium, and the start point (the IN point) and the end point (the OUT point) are marked. Thereafter, a plurality of video clips based on the IN point and the OUT point of each of the clips are connected together. Thus, video formed from the desired video clips that are continuously connected is obtained.
In general, edit data and the base data are compression encoded using a predetermined method. The data is separated into data blocks having a predetermined size (data size) and recorded onto a recording medium. When the AV data is recorded onto the recording medium, the header information and the footer information are written to the recorded AV data. While the AV data is being edited, the header information and the footer information are updated in accordance with an operation of editing.
In addition, the above-described IN point and OUT point are input to an input unit used for editing and are transmitted to an editing apparatus via a communication interface. For example, the IN point is specified by an EDIT ON signal, and the OUT point is specified by an EDIT OFF signal. Upon receiving the EDIT ON signal or EDIT OFF signal, the editing apparatus controls each of the components of the editing apparatus to start editing or stop editing. Thus, an editing operation is performed.
As used herein, a data chunk for which it is necessary for an application that handles AV data to continuously play back, that is, a data chunk that is to be played back in real time is referred to as a “clip”. An example of a clip is a data chunk obtained from start to end of image capturing performed by a video camera. In reality, a clip is in the form of a single file or a plurality of files. In addition, a file system (FS) is disposed at each of the logical addresses of the top and end of the recording medium. Any data is recorded in the logical address space in a predetermined format called a “file”. In general, such data on the recording medium is managed on a per file basis. The management information of the file is recorded in the file system. Accordingly, a control unit of a video and audio recording apparatus can manage a variety of types of data on a recording medium by referring to and handling the information in the file system.
Furthermore, when the sizes of the data blocks of the video/audio data are the same (a fixed length), existing video and audio recording apparatuses can perform destructive insert editing in real time by overwriting edit video data and audio data onto the base data. As used herein, an original file to which video data and audio data are overwritten is referred to as a “base file”. In addition, the data of the file is referred to as “base data”. The video data and audio data that are overwritten onto the base data are referred to as “edit data”. Furthermore, logically overwrite editing in which part of the base data is logically deleted and the edit data is inserted into the deleted area is referred to as “destructive insert editing” or simply “destructive editing”.
As described above, destructive editing is performed using the file system. The “file system” manages information regarding the physical position of a data block stored in a file and management information regarding logical links among the data blocks. In this example, when video data is transferred at a transfer rate of 50 Mbps and the audio data has a 24-bit/8-channel format, the size of data contained in a data block is 15.8 Mbytes. In addition, each of the audio data and the video data contained in a data block corresponds to data having a playback time of about 2 seconds.
FIGS. 9A to 9C illustrate an example of existing video editing. More specifically, FIG. 9A illustrates an example of the structure of a base file 100. The base file 100 includes a plurality of data blocks. Each of the data blocks includes a proxy/RT field 101 (“RT” stands for real time meta data), an audio field 102, and a video field 103. The fields 101 to 103 have a fixed length. In addition, the data blocks have a fixed length.
FIG. 9B illustrates an example of destructive editing performed on video data included in the base file 100. In this example, data in the middle of the video field 103 is overwritten with new video data 106. In destructive editing of the video data 106, the start point is defined when an IN point 104 is specified using an external controller, and the end point is defined when an OUT point 105 is specified. Thereafter, the video fields 103 located from the IN point 104 to the OUT point 105 are overwritten with the video data 106 serving as edit data.
FIG. 9C illustrates an example of a file system 107. The file system 107 manages the size of data of the proxy/RT field 101, the audio field 102, and the video field 103, each having a fixed length, included in the base file 100. Accordingly, as shown in FIG. 9B, even when the part starting from the middle of the video field 103 is overwritten with the video data 106, the data size of each of the fields remains unchanged. Consequently, it is not necessary to update the file system 107. Thus, even when the video field 103 is simply overwritten with the video data 106, the video data functions as an edited base file 100. This also applies to the case in which audio data included in the audio field 102 is subjected to destructive editing.
Japanese Unexamined Patent Application Publication No. 2008-53839 describes a technique for editing video using an editing apparatus and a video recording and reproducing apparatus disposed on the reproducing side and the recording side.
Japanese Unexamined Patent Application Publication No. 2006-140722 describes a technique for recovering inconsistency between data items recorded in a recording medium even when recording of data is abnormally terminated.